Ca2+ signaling in endothelial cells stimulated by bradykinin: Ca2+ measurement in the mitochondria and the cytosol by confocal microscopy

Cell Calcium. 1996 Jul;20(1):53-61. doi: 10.1016/s0143-4160(96)90050-0.


In this study we have monitored the change of intracellular Ca2+ concentrations in the cytosol ([Ca2+]c) and the mitochondria ([Ca2+]m) of single bovine endothelial cells following treatment with bradykinin (BK). Using laser scanning confocal microscopy, we have found that the Ca2+ indicator, Fluo-3, is compartmentalized in the mitochondria of endothelial cells loaded with Fluo-3/AM. After BK stimulation, the pattern of Ca2+ increase in the cytosol is different from that in the mitochondria. The amplitude of the Ca2+ rise in the mitochondria is higher than that in the cytosol. Further analysis using rapid scanning measurements indicates that the [Ca2+]c increase is very fast after BK addition and reaches a maxima level within 400 ms. In contrast, the [Ca2+]m increase appears to be biphasic with an initial rapid increase (concomitant with the [Ca2+]c increase) followed by a slower [Ca2+]m increase before reaching a maximal level (within 5 s of BK treatment). The differential Ca2+ signaling pattern between the cytosol and the mitochondria suggests that the intracellular Ca2+ concentrations needed to regulate various Ca(2+)-dependent enzymes located in these two compartments are different during BK-induced endothelial cell activation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aniline Compounds
  • Animals
  • Bradykinin / pharmacology*
  • Calcium / physiology*
  • Cattle
  • Cell Compartmentation
  • Cytosol / chemistry
  • Endothelium, Vascular / cytology*
  • Endothelium, Vascular / ultrastructure
  • Fluorescent Dyes
  • Kinetics
  • Microscopy, Confocal
  • Mitochondria / chemistry
  • Signal Transduction / drug effects
  • Xanthenes


  • Aniline Compounds
  • Fluorescent Dyes
  • Xanthenes
  • Fluo-3
  • Bradykinin
  • Calcium